Desulfurizing cast-iron



citizen ofthe United States,

--oanLnzroN ELLIS, or moNrcLAm, NEW masnr, assrenon p coarone'rron or NEW JERSEY.

nnsonromzme' oa's'r-Iaon.

No Drawing.

To all whom it may concern:

Be it known that 1, Carmen Exams, 8. and a resident of Montclair, in the count of Essex and State of New Jersey, have mvented certain new and useful Improvements in Desulfurplicated and expensive equipment and'careizing Cast-Iron, of which the following is a specification. Y a a This invention relates to a process of de-' sulfurizing cast iron and the like and has to do particularly with the treatment of sulfurbearing cast iron, with calcium or similar element, in the form of a compound'with certain other elements which enable the full i been charged example,- .9% of "is made by melting scrap.

- stances.

reactive. ualities of the element calcium to be exerte in desulfurization. "The method also may be employedv in the case of iron containing phosphorus and. silicon in excessive quantities. v

A goodpart of the 110Il cast. in, foundries nary pig iron is added butoften a large part of or the entire charge in the cupola is scrap iron stock. This is melted by means of coke containing sulfur, and acertain amount of sulfur thus is imparted to the cast iron each time a charge is run. each time scrap iron is re'melted, su

entire suppl of pig iron is increasing in average sulur content through such repeated melting. Furthermore the coke available at many points is, if. anything, tending gradually to run higherin sulfur, which aggravates the condition. After iron has with a certain amount of sulhot short and has other ob- Usually a proportion of sulfur of above one per cent. renders the iron unworkable for many purposes. For

sulfur is the maximum permitted in certain. cases. to blow air through the molten ironin a converter, especially one equipped with a basic lining to oxidize andremove the sulfur and produce a species of steel or pure iron which'may be incorporated with some of the original iron so that the resulting melt contains less than 1% of sulfur, or whatever the maximum sulfur content may be permitted under the circum- By such blowing operation the content of carbon is usually reduced, some times to an undesirable point and powdered coal or coke or other form of carbon may fur it becomes jectionable qualltles.

amount of sulfur It is possible Specification of Letters latent.

not feasible in ordinary foundry and 1n the present invention the o ject 'is' Sometimes ordi-' 'Conse' uently fur is introduced and therefore it follows that the Patented Mar. 30, 1920.

Application med octow a, 1917. Serial nojiaassz.

be added to the iron until its content of carbon is brought up to the requisite point.

Or the blown iron practically-free-from sulfur and silic a' may be recarbur-ized by treatment with coal or coke. p Such a procedure however, involves comful operation and'control such as often is ractice more particularly to provide amea'ns for treatmg sulfur containing iron in the ladle or other container into which the molten iron is run, forexam 1e, from the cupola or n some other simp e way; contaotin the sulfur-containing iron wit the desul rizing rea ent'so as to enable the process-to be use in ordinary .foundry operations wi trlfiiut complicated apparatus.

'ro ELLIs-rosrna co.-, a i

agent w ieh 'I prefer" in,"the present mvention; is av calcium compound oontaining the element calcium in such. state as to readily combine with sulfur, phosphorus,

silicon, and the like and having no other element 1n combination with the calcium which would be objectionable in the'iron.

For example-I may use calcium 0 as a desulfurizing agent and w en this comes in contact with molten cast iron and reacts. with the sulfur therein the carbon and nitrogen of the cyanamid are not objectionable constituents under these conditions. If on the other hand, molteniron-is treated with calcium" oxid the effect is rather to'produce a slag with silicious material than to bring about an effective combination with sulfur. Metallic calcium would be an excellent desulfurizing agent from the standpoint of efiiciency but is too expensive. Oxids of calcium are far'less active because the afiinity of the calcium is already satis fied to a large extent by the oxygen with which it is combined. In the case of calcium cyanamid, however, the combination is not anamid a highly stable one and the calcium is much.

more free to combine with thesulfur es ecially in view ofthe aflinity of iron ibr carbon. By the use of material such as calcium carbid or calcium cyanamid the effect of metallic calcium is obtained in a way without resortin to anything as expensive and as difiicu t to preserve as calcium in the metallic state. I

The reagent may be mixed in lump or powdered form with the iron in theform of turnings, shavings and the like, and may be melted to'bring about the reaction or the product may be placed in the bottom of the ladle and themolten iron from the cupola, or other container run therein, when reaction takes place. Or the ladle may be lined with a mixturecomprising calcium carbid, calcium cyanamid or similar calcium com; pound. Or the iron may be allowed to flow along a trough lined with material containing the canbid, nitrid or the like.

In one casethe treatment of cast iron with 7 calcium carbid, the original content of the iron being 0.93% sulfur and 2.42% silicon, the sulfur was reduced to 0.65% and the silicon to 1.93%. Similarl with calcium cyanamida ieduction in su fur and silicon con tent occurred, the degree of reduction in the case of the silicon being greater than with the'calcium ca'rbid employed under the conditions of the test.

Thus it will be seen that the essence of the invention consists intreating under suitable reacting conditions cast iron containing sulfur, phosphorus, silicon and the like, (one or moreof these impurifying elements. being I present, as the case may be) with a reagent,

namely, a, compound containing an element ofa basic character such as the alkaline earthmetals, namely: magnesium, calcium, barium, etc., or even the alkali metals such as sodium in combination with an element or radical which yieldsa compound capable of being readily handled but which does not impair to anyobjectionable extent the reactivity of the basic element in question. For

example, the elements calcium, barium, so-

dium-and the like, may e combined with carbon to form a carbid; with nitrogen, to

make a nitrid; with hydrogen, to yield a hydrid; with carbon and nitrogen, in the case of calcium, for instance, togive the cyanamid. Preferably the elementof calcium or other alkali material is combined as slag.

with a non-metallic element or metalloid or grouping of metalloidal elements. Hence the carbid or nitrid, for example, has a prefwhich comprises bringing calcium cyanamid into contact with the molten metal.

2.- The process of desulfurizing. cast iron which comprises running molten cast iron containing sulfur into a ladle containing calcium cyanamid,

3. The process of desulfuri'zing cast iron which comprises bringing a basic cyanamid into contact with the molten metal the base of said cyanamid being capable of uniting with someportion at least of the sulfur in the ast iron and separating from the latter 4. The process of desulfurizing cast iron which comprises running molten cast iron containing sulfur into a ladle containing a basic cyanamid, the base of said'cyanamid being capable of uniting with some portion at least of the sulfur inv the cast ironand separating from the latter as slag. I

5. The process of desulfurizing cast iron which comprises bringing molten cast iron containing'sulfur into contact with a mixture comprising calciumcyanamid and calcium carbid.

6. The process of desulfurizing cast iron which comprises bringing into contact with the molten metal a desulfurizing agent comprising calcium united with an element whose liberation in the iron does not materially afl'ect the qualit thereof.

' (l ARLE TON ELLIS. 

